ASTM F1869 is the calcium chloride moisture test — the long-established method for measuring moisture vapor emission rate (MVER) from a concrete slab surface. Here is what it measures, how it works, and when to use it.
What ASTM F1869 measures
ASTM F1869 measures the moisture vapor emission rate (MVER) from the surface of a concrete slab, expressed in pounds of moisture per 1,000 square feet over 24 hours. The test captures surface-level moisture movement over a defined period using an anhydrous calcium chloride kit sealed under a dome on the slab surface. The weight gain of the calcium chloride is converted to an MVER rate.
When the calcium chloride test is used
F1869 is used when the project specification or flooring manufacturer requires an MVER value — many flooring installation standards still reference this method, and it remains the baseline test for numerous commercial flooring systems. It is surface-focused, making it appropriate when the project team needs to understand current emission conditions at the slab surface prior to installation. Review IFTI’s F2170 vs F1869 comparison to understand when each is the right choice.
How the test is performed
The test requires properly prepared, bare concrete — no coatings, sealers, adhesive residue, or surface contamination. A pre-weighed dish of anhydrous calcium chloride is placed on the slab and covered with a sealed plastic dome for the period specified by the standard (typically 60–72 hours per the current test method). The dome is sealed to the slab with putty to prevent ambient air movement from affecting the reading. After the test period, the dish is removed and re-weighed; the weight gain determines the MVER. Ambient temperature and relative humidity conditions must be recorded and reported, as they significantly affect results.
Interpreting MVER for flooring
The MVER result must be compared to the flooring manufacturer’s specified maximum allowable MVER for the specific product being installed. If the measured MVER exceeds the limit, installation must be delayed, drying conditions improved, or a manufacturer-approved mitigation system installed before proceeding. Document all readings, conditions, and decisions. See IFTI’s moisture vapor emission rate guide and concrete moisture testing services.
Limitations and common failure modes
F1869 is surface-based, which means it can misrepresent the internal moisture conditions of the slab — the slab surface may show acceptable emission while the interior still holds moisture that will continue releasing after flooring is installed. The test is also sensitive to ambient temperature and humidity at the time of testing; the conditions must be within the standard’s requirements for results to be valid. For slabs on grade in areas with high groundwater or prior flooding history, internal RH testing (F2170) provides better predictive data on long-term performance risk.
F1869 vs F2170 decision framework
Use F1869 when the spec or manufacturer requires MVER in pounds, and use F2170 when the spec or manufacturer requires internal RH. When long-term risk is high — slabs below grade, slabs with prior water events, or high-value flooring systems — running both tests provides the most complete picture. The governing requirement is always the flooring manufacturer’s written installation specification, not a general preference.
Frequently Asked Questions
What does MVER stand for?
Moisture Vapor Emission Rate — the rate at which moisture is leaving the surface of a concrete slab, expressed in pounds per 1,000 square feet over 24 hours.
What units does F1869 use?
Pounds of moisture per 1,000 square feet over 24 hours.
Is F1869 the same as RH testing?
No. F1869 is a surface emission test (MVER); ASTM F2170 is an internal relative humidity test. They measure different things and are not interchangeable.
Can coatings affect the calcium chloride result?
Yes. Any coating, sealer, adhesive residue, or contamination on the slab surface must be removed before testing. The standard requires properly prepared, bare concrete for valid results.
What if MVER is too high?
Delay installation, improve drying conditions, or install a manufacturer-approved mitigation system. Document all conditions and the decision before proceeding.
